David Sarnoff was born in Uzliany shtetl near Minsk, Russia (now in Belarus) to a poor Jewish family. Most of his early childhood was spent studying talmud. He emigrated to the United States in 1900, and was forced to work to feed his parents and siblings by selling Yiddish-language newspapers in New York City. He joined the Marconi Wireless Company in 1906, and studied electrical engineering at the Pratt Institute. When he was 21 he had a job as telegraph operator at the Wanamaker Department Store. Sarnoff later claimed that he was one of the operators who picked up news of the sinking of Titanic. This story was shown to be not true. The station was closed the Sunday night that the Titanic sank. Sarnoff did not report for work until the next day, and within the next 24 hours the Marconi Company closed down all their stations except for four, to prevent interference. The Wanamaker station was among those closed down. Whether or not it is true, Sarnoff repeated the claim often enough to earn himself a reputation.

When he was put in charge of radio broadcasting at RCA, he soon recognized the potential of television. He was determined for his company to take control of the development of the new medium. He met with Westinghouse engineer Vladimir Zworykin in late 1928, who was trying to develop an all-electronic television system in his spare time on the company premises. Zworykin told Sarnoff he could build a viable television system with a mere $100,000 grant in two years. Sarnoff decided to fund this research but would later discover that Zworykin's estimate was far too optimistic, off by several orders of magnitude and several years.

Sarnoff became president of RCA on January 3, 1930. On May 30 the company was involved in an antitrust case concerning the original radio patent pool. Sarnoff was able to negotiate an outcome where RCA was no longer partly owned by Westinghouse and General Electric, giving him final say in the company's affairs.

Initially, the Great Depression caused RCA to cut costs, but Zworykin's television research which began in earnest in 1930 was protected by Sarnoff. After years of hard work, Sarnoff's support and Zworykin's genius (and the genius of several members of the growing RCA television research team), RCA had a commercial system ready to launch. RCA's early developments were largely done in secret, however an article of 1933 by Zworykin sheds some light on this earliest work. RCA initially demonstrated a working Iconoscope camera tube and Kinescope receiver tube to the press on April 24, 1936. The final cost of the enterprise was close to $50 million.

RCA purchased many television patents from other inventors. The most important patents purchased were likely those of 1928 priority by Kalman Tihanyi. Due to the young genius inventor Philo T. Farnsworth, who refused to sell his patents to RCA, there were endless lawsuits and additional research costs involved, as RCA tried to engineer their way around Farnsworth's patents. In 1931, Sarnoff paid a personal visit to Farnsworth's San Francisco Laboratory, offering to purchase his television patents outright for $100,000. Farnsworth refused, insisting on a patent-licensing agreement. This resulted in a stalemate.

Meanwhile, an all-electronic television system began to be developed by the British firm EMI. This was initially based on Tihanyi's work and helped considerably by RCA patents. The Marconi-EMI system was developed in Britain and first used by the BBC in 1936. World War II halted television broadcasting from BBC London on September 1st, 1939.

Delayed in part by the patent lawsuits with Farnsworth, American all-electronic television broadcasts finally began at the Spring opening of the 1939 New York World's Fair, with the famous speech given by Sarnoff "Now ... we add sight to sound". Along with a small number of other TV manufacturers, RCA marketed 4 different types of pre-war television receivers to the public. Sales were slow due to the lack of programs. During WWII, Sarnoff was Eisenhower's top communications expert, overseeing the construction of a radio transmitter that was powerful enough to reach all of the allied forces in Europe. He campaigned for, and received, the honorary title of Brigadier General, and thereafter preferred to be known as "General Sarnoff".

After the war, monochrome television broadcasting and receiver production recommenced almost immediately. Color television was the next major development and CBS had their partly-mechanical colour television system approved by the FCC on October 10, 1950. Sarnoff filed an unsuccessful suit in the United States district court to suspend the ruling. He made an appeal to the Supreme court which also upheld the FCC decision. Sarnoff pushed his engineers to perfect an all-electronic colour television system that used a signal that could be received on existing monochrome sets. CBS was unable to take advantage of the color market, due to lack of manufacturing capability and sets that were triple the cost of monochrome sets. A few days after CBS had its color premiere on 14 June 1951, RCA demonstrated a fully functional all-electronic color television system.

Color television production was suspended on October 1951 for the duration of the Korean War. As more people bought monochrome sets, it was increasingly unlikely that CBS could achieve any success with its incompatible system. The NTSC was reformed and recommended a system virtually identical to RCA's in August 1952. On December 17, 1953 the FCC approved RCA's system as the new standard. The early colour sets were expensive, unreliable, and RCA's early shadowmask screen robbed some of the picture's brightness and detail. Only a few programs per week were broadcast in colour. Several years passed before colour televisions sold as well as black-and-white sets.

Sarnoff retired in 1970, at the age of 79, and died the subsequent year.